<template>
  <div class="subject">
    <span>{{num1}}</span>
    <span>+</span>
    <span>{{num2}}</span>
    <span>=</span>
    <input
      type="number"
      v-model.number="result"
      :disabled='isDis'
    />
    <button
      @click="submitFn"
      :disabled='isDis'
    >提交</button>
  </div>
</template>

<script>
export default {
  props: ['index'],
  data () {
    return {
      num1: Math.floor(Math.random() * (20 - 0 + 1) + 0),
      num2: Math.floor(Math.random() * (20 - 0 + 1) + 0),
      result: null,
      isDis: false
    }
  },
  methods: {
    submitFn () {
      this.isDis = true
      let resultStr = ((this.num1 + this.num2) == this.result) ? '正确' : '错误';
      this.$emit('result', resultStr, this.index)
    }
  }
};
</script>

<style scoped>
.subject {
  margin: 5px;
  padding: 5px;
  font-size: 20px;
}
.subject span {
  display: inline-block;
  text-align: center;
  width: 20px;
}
.subject input {
  width: 50px;
  height: 20px;
}
</style>